Transistor and semiconductor device

Abstract

A transistor is provided, which is entirely and partially transparent by the use of a transparent channel layer made of zinc oxide or the like. A channel layer 11 formed of a transparent semiconductor such as zinc oxide ZnO. A transparent electrode is used for all of a source 12, a drain 13 and a gate 14, or a part of them. As the transparent electrode, a transparent conductive material such as conductive ZnO doped with, for example, group III elements is used. As a gate insulating layer 15, a transparent insulative material such as insulative ZnO doped with elements capable of taking a valence of one as a valence number or group V elements is used. If a substrate 16 must be transparent, for example, glass, sapphire, plastic or the like can be used as a transparent material.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a transistor and a semiconductor device, more particularly to a transparent transistor, a semiconductor device having the transparent transistor stacked thereon, and a semiconductor device to which the transparent transistor is applied for driving a light emission device, for reading / writing data from / to a memory, and for other purposes. It should be noted that in the present invention, a concept of “transparent” includes a concept of “being transparent or offering light transmission property” for the sake of simplifying descriptions. DESCRIPTIONS OF THE RELATED ARTS [0002] A thin film transistor using amorphous silicon, polycrystalline silicon or the like has been generally used as a transistor for use in driving liquid crystal display devices. Since these materials exhibit photosensitivity for the visible light region, carriers are generated by a beam of light, and resistivity of a thin film constituting the thin film ...

AI Technical Summary

Benefits of technology

[0003] Generally, the liquid crystal display device has been widely used for a notebook type personal computer or the like, and an energy-saving measure, a high luminance and a miniaturization have been requested of the liquid crystal display device. To reply to these requests, it is effective to increase a rate of an effective area of a display portion within a unit pixel. However, since a light shielding layer made of a metal thin film or the like in the transistor for driving the liquid crystal display device is formed as described above, a rate of an area of a light transmission portion to that of the light shielding layer (opening ratio) in the pixel reduces. Accordingly, a reduction of a transistor area by improving a performance of the transistor or an improvement of luminance of a backlight are necessary to develop a display device having high luminance. However, the measure to improve the characteristic of the transistor shows a limitation to a yield, leading to an increase in cost. Moreover, the measure to improve the luminance of the backlight increases an amount of energy consumption.

[0004] From the viewpoint of the above described points, the object of the present invention is to provide a transistor using a transparent channel layer made of zinc oxide or the like, which is transparent partially or entirely, because an orientation control of the zinc oxide and a valence electron control thereof that has been heretofore difficult is now possible. Specifically, the object of the present invention is to provide a transistor which uses a transparent material such as the zinc oxide or the like for a channel layer (conductive layer) so that the channel layer does not have a photosensitivity for the visible light region, and removes a necessity to form a light shielding layer, thus increasing an area rate of a display portion of a liquid crystal display device or the like.

Problems solved by technology

However, the measure to improve the characteristic of the transistor shows a limitation to a yield, leading to an increase in cost.

Moreover, the measure to improve the luminance of the backlight increases an amount of energy consumption.

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